"Tojo" was one of the few Japanese
fighters to
emphasize speed and climb rate over maneuverability, making it the
mainstay of Japanese interceptor defenses when the Americanstrategic bombing campaign
got under way. It had
a poor view
on takeoff and poor control, so that it killed a number of
inexperienced
pilots. However, it could
climb and dive as well as most of
its
enemies. The wing loading was unusually high for a Japanese aircraft,
which was partially compensated with butterfly combat flaps. The
armor and self-sealing fuel tanks
proved inadequate against the heavy
machine guns of Allied
fighters.

The design dated to January 1940, when the
Japanese Army asked Nakajima to design an interceptor to complement the
Ki-43 "Oscar". The design team, led by
Koyama Yasushi, designed the new aircraft around the Ha-41 engine, which was
more powerful than the Ha-25
that was becoming standard on fighters. The team were able to meet the
challenge of matching this rather large engine, originally designed for
bombers, to a narrow fuselage, and the aircraft had a large fuselage
side area and horizontal tail surfaces well forward of the rudder to
improve its qualities as a gun platform. The first prototype flew in
August 1940, and after modifications to reduce drag, nine service
prototypes were deployed to 47 Squadron
in China for field testing just
before war broke out in the Pacific. A small production run began in
January 1942, but the inability of these aircraft to intercept the
Army's own high-altitude reconnaissance aircraft
let the Army to insist on further design work, and the definitive
Ki-44-IIb did not begin production before November 1942.

Although "Tojo" was disliked by veteran pilots for
its high landing speed and relatively poor maneuverability, younger
pilots learned to make good use of its climb and dive speed. The -IIc
was probably the most successful interceptor
of B-29s,
though some of its kills were achieved
by deliberate ramming. However,
the aircraft began to be replaced by the Ki-84
"Frank" in late 1944.